1. Field of the Invention
The present invention relates to watercraft, and more particularly to a thrust reversing bucket for low speed maneuvering including reverse, neutral, side and forward thrust motion of a boat with a propeller.
2. Description of the Related Art
The term thrust bucket or thrust reversing bucket is carryover language from jet engines for airplanes or water jet pump propulsion systems for boats. Existing thrust buckets maintain the water velocity at an orderly, high speed flow and simply curves the flow into another direction to slow down the jet boat or maneuver the jet boat rearward or sideways as desired. In water jet applications, the velocity energy is maintained relatively constant as the water goes through the bucket. Most conventional thrust buckets were used on water jet propulsion boats because the water pump impeller rotation cannot be effectively reversed. Conventional thrust reversing buckets for water pump jet drives do not contemplate a propeller.
Thrust buckets were rarely used on propeller driven boats because reverse rotation of the propeller together with steering the propeller or rudder usually sufficed for low speed maneuvering in the reverse direction or for slowing down the forward motion of the boat.
There are a few thrust reversing bucket type systems designed for propeller driven boats. One thrust reversing bucket for a propeller has directional control but requires that the thrust bucket be partially withdrawn from the propeller discharge to vary the ratio of forward thrust to rearward thrust. This system uses a single diverter vane that is common to two separate discharges comprised of a port water course and a starboard water course. In other designs, the entire bucket tilts or turns to deflect the propeller flow. Also, other conventional thrust buckets do not retract the mechanism fully from the propeller under high speed forward operation of a boat, but rather some or all of the mechanisms stay in the water as a propeller shroud or side rudder and cause a continuous force on the boat. And lastly, existing deployable thrust buckets do not have an annulus in the plane of the propeller to capture and contain the flow of water from the propeller and which can be retracted to a position wherein it does not affect the force on the boat.
Usually, the higher the design speed of a boat, the more specialized is the propeller. These high speed propellers have blades which are asymmetric and perform poorly when operating in reverse rotation. One such type of propeller is known as a “cleaver” propeller. Slow speed maneuvering of such boats has been particularly difficult. In general, nearly all of the operation of a typical boat is in the forward direction and at a high rate of speed. However, there are occasions, even for high speed boat designs, when low speed maneuverability is desirable. Conventional types of propulsion are deficient in maneuvering when operating in low speed mode. Although it is understood that only a small portion of time is spent reversing or side maneuvering in a docking or undocking situation, good maneuvering is an important benefit to safety and operability